background_tasks.h File Reference

Background task scheduler. More...

#include <stdint.h>

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Macros
#define	F_TIMER   20000
	Frequency of the CPU timer used in by the task scheduler in [Hz]. More...
#define	F_TASK_FAST   F_TIMER
	High priority task: Called every 50 us (20 kHz) More...
#define	F_TASK_MID   (F_TASK_FAST / 20)
	Medium priority task: Called every 1 ms (1 kHz) More...
#define	F_TASK_SLOW   (F_TASK_MID / 10)
	Low priority task: Called every 10 ms (100 Hz) More...

Typedefs
typedef void(*	background_task_t) (void)
	Data type for background task pointers. More...

Functions
void	process_background_tasks (void)
	Invokes registered background tasks if certain conditions are met. More...
void	init_background_tasks (background_task_t high_freq_tasks[], uint8_t high_freq_tasks_size, background_task_t mid_freq_tasks[], uint8_t mid_freq_tasks_size, background_task_t low_freq_tasks[], uint8_t low_freq_tasks_size)
	Initializes the background task scheduler. More...

Detailed Description

Background task scheduler.

Macro Definition Documentation

F_TASK_FAST

#define F_TASK_FAST   F_TIMER

High priority task: Called every 50 us (20 kHz)

F_TASK_MID

#define F_TASK_MID   (F_TASK_FAST / 20)

Medium priority task: Called every 1 ms (1 kHz)

F_TASK_SLOW

#define F_TASK_SLOW   (F_TASK_MID / 10)

Low priority task: Called every 10 ms (100 Hz)

F_TIMER

#define F_TIMER   20000

Frequency of the CPU timer used in by the task scheduler in [Hz].

Typedef Documentation

background_task_t

typedef void(* background_task_t) (void)

Data type for background task pointers.

Function Documentation

init_background_tasks()

void init_background_tasks	(	background_task_t	high_freq_tasks[],
		uint8_t	high_freq_tasks_size,
		background_task_t	mid_freq_tasks[],
		uint8_t	mid_freq_tasks_size,
		background_task_t	low_freq_tasks[],
		uint8_t	low_freq_tasks_size
	)

Initializes the background task scheduler.

Configures CPU timer 0 to provide the main clock for the background task scheduler and registers the tasks to be invoked cyclically. The tasks are grouped into three levels of priority. High priority tasks are executed more frequently.

Parameters

high_freq_tasks	an array of function pointers to high frequency tasks
high_freq_tasks_size	number of high frequency tasks
mid_freq_tasks	an array of function pointers to medium frequency tasks
mid_freq_tasks_size	number of medium frequency tasks
low_freq_tasks	an array of function pointers to low frequency tasks
low_freq_tasks_size	number of low frequency tasks

See also

F_TASK_FAST

F_TASK_MID

F_TASK_SLOW

process_background_tasks()

void process_background_tasks

(

void

)

Invokes registered background tasks if certain conditions are met.

This procedure must be called in the main loop of the program. If the CPU timer interrupt flag of CPU timer 0 is active, it is reset and the prescaler counters are incremented. If one of the prescalers reaches its target value, it is reset as well and the corresponding tasks are executed one by one.

See also

F_TASK_FAST

F_TASK_MID

F_TASK_SLOW